The Concord boy had noticed the scow come across the river earlier in the day. The pilot to which it was attached by a stout cable was a large yawl, with three pairs of oars manned by stalwart redcoats. They had come across the stream to gather forage for their horses, selecting a spot where a coarse swamp hay grew thickly. Andy had told Phil this back at the camp at Cambridge, and his comrade had made his arrangements accordingly. His commanding officer had given Phil a letter to deliver in Boston. Phil's Musket Boys chums had sent a cheering word to their parents, and, assuming their old civilian clothes, Phil and Andy had started out on the desperate enterprise of trying to rescue Mr. Warrington and his fellow prisoners from the hands of the British. Now they had made a favorable start in their project, and it looked very much as if the hardest part of their task, crossing the river to Boston, had been accomplished. The boys lay snug and contented, conversing in whispers when there was occasion for talk. After a while the scow began to move. They gazed out from their screen of hay to watch the shore they had just left fade from view. There was slow and hampered progress when they met the strong central current of the broad Charles River. After that the scow proceeded steadily on its course. As it turned now and then they could make out the river docks and the lights of the city. Then the scow sided up against a wharf bulkhead and became motionless. "What now?" inquired Phil of his companion. "We seem to have arrived for good. The boat has brought us over. How are we going to leave it?" "I'll reconnoitre a bit, I guess," answered Andy, and he began to cautiously work his way beyond the hay into the open starlight. Then he trod along the extreme edge of the well-loaded craft, and managed to reach the side of its deck without accident. Andy took a look down the wharf, and then bobbed back quickly. He returned as fast as he could to Phil. "The fellows in the pilot yawl have cut loose and are rowing up the river," he informed his chum, "but a new crowd of men has just come out from sheds in a big hay yard to unload. There may be twenty of them--big roystering fellows. They've got pitchforks, and will start right at work. Let's get out of this, Phil." Andy at once led the way along his recent course, whispering his plan to Phil to spring up on the wharf and make a run for it. A high fence set back about four feet lined the wharf. It had no break for some distance. "Come on now--hold on!" said Andy, peering past the side of the scow. "Thunder, Phil! smell that? see that?" Smoke was what both boys instantly scented. A flare it was that dazzled their eyes. Loud shouts greeted their startled hearing. Some careless smoker among the unloading gang had set fire to the great load of hay.